This invention relates to electrical welders.
Arc welders are in widespread use, industrially and domestically. Such devices are powered by a single- or three-phase mains supply, or by a generating set or d.c. supply. Usually it is necessary to transform the supply voltage to a level suited for welding applications.
The welding transformers in use for this purpose are bulky and heavy and must either be tapped or be formed with a variable reactance core to provide a range of possible welding currents.
Various welders known to the applicant are described in the specifications of U.S.A. Pat. Nos. 3,211,953, 3,231,711, 3,304,485, 3,518,401, 3,818,177, 4,038,515, 4,047,096 and 4,117,303.